A practical joke, or prank, is a mischievous trick played on someone, generally causing the victim to experience embarrassment, perplexity, confusion, or discomfort. A person who performs a practical joke is called a "practical joker" or "prankster". Other terms for practical jokes include gag, rib, jape, or shenanigan.

Practical jokes differ from confidence tricks or hoaxes in that the victim finds out, or is let in on the joke, rather than being talked into handing over money or other valuables. Practical jokes are generally lighthearted and without lasting effect; they aim to make the victim feel humbled or foolish, but not victimized or humiliated. Thus most practical jokes are affectionate gestures of humour and designed to encourage laughter. However, practical jokes performed with cruelty can constitute bullying, whose intent is to harass or exclude rather than reinforce social bonds through ritual humbling.

Some countries in Western culture traditionally emphasize the carrying out of practical jokes on April Fools' Day and Mischief Night.